1. Field of the Invention
The present invention relates to an optical interconnect technology that uses light for data transmission within a substrate as well as an optical module assembly in which optical modules have an improved structure and an optical wiring board.
2. Description of the Related Art
Recently, for information processing devices such as servers, routers, and storages, there is a growing need to speed up data transmission within a device or board. Data transmission within these devices is on the verge of change from conventional electrical transmission to optical transmission that enables higher speed transmission.
Information processing devices have several circuit boards installed on a back plane, including a switch board, a blade board, etc. On these boards, LSIs such as a switch LSI, interface module, and CPU are mounted. These circuit boards are connected to the back plane and signal transmission between these boards is performed. Within a circuit board, signal transmission between an LSI and a connector is also performed. For signal transmission within a circuit board, electrical transmission via electrical wiring has so far been used. However, electrical transmission encounters a difficulty in speeding up, because increasing transmission speed causes an increase in loss across wiring on the board and gives rise to a cross talk. Consequently, the use of optical transmission for signal transmission with a circuit board is pursued.
Regarding the use of an optical interconnect technology for signal transmission within a circuit board, in Japanese Unexamined Patent Application Publication No. 2009-198921, there is a description as follows: “An optical module that optically connects an optical transmission path for transmitting an optical signal and an optical element converting an optical signal to an electrical signal and vice versa, comprising an upper structure provided with an optical transmission body and a support member supporting the optical transmission body, a wiring board provided with wiring patterns and connecting electrodes, an electronic components mounting board which is placed over the wiring board and in which electronic components including an optical element are mounted on its top surface and underside electrodes which are electrically connected to the electronic components' electrodes are provided on its under surface, a fitting body which optically connects the optical transmission path in the upper structure to the optical element in the electronic components mounting board and contacts and electrically connects the underside electrodes of the electronic components mounting board and the connecting electrodes of the wiring board by vertically pressing and fixing the upper structure and the electronic components mounting board onto the wiring board, characterized in that the underside electrodes of the electronic components mounting board or the connecting electrodes of the wiring board are formed to protrude.” (Claim 1)
In Japanese Unexamined Patent Application Publication No. 2001-196625, a board to board interconnection device is described in which a chip carrier on which a ferrule embracing a lens array and a semiconductor laser or photo diode are mounted is supported on a wiring board via elastic bodies. There is also a description that the elastic bodies support the chip carrier vertically to the main surface of the wiring board and pressure is exerted toward an optical axis direction in a split sleeve, when connecting a ferrule of an optical transmitter unit in a first wiring board and a ferrule of an optical receiver unit in a second wiring board. (Claims 1 and 2)